Numerical Investigation on Spent Beam Deceleration Schemes for Depressed Collector of a High-Power Gyrotron

Single-stage depressed collector systems are widely used in high-power gyrotrons in order to increase the overall efficiency. The position where the deceleration of the beam takes place influences the collector efficiency. In this paper, several deceleration schemes are numerically investigated for the short-pulse prototype of the 170-GHz, 1-MW European gyrotron for International Thermonuclear Experimental Reactor. The results of this paper are in a qualitative agreement with the results of dedicated experiments. A simple idea is also proposed for the significant increase of the overall gyrotron efficiency without an important technological modification.